Field of the Invention
The present invention relates to an apparatus for driving sensors consisting of a plurality of lines and, more particularly, to a sensor drive apparatus to realize a miniaturization of the apparatus scale, a high speed operation, and the like.
Related Background Art
FIG. 4 is a diagram showing a schematic arrangement of a conventional sensor drive circuit.
In the conventional example, scanning circuits 1 to 3 are provided for color line sensors 1 to 3, respectively. Therefore, the line sensors can be independently driven by shifting the timings of start pulses .phi..sub.s1 to .phi..sub.s3 of the scanning circuits.
That is, by supplying the start pulse .phi..sub.s1 and drive pulses .phi..sub.1 and .phi..sub.2, the scanning circuit 1 is made operative and the line sensor 1 is driven and a sensor signal O.sub.1 is output through an amplifier A.sub.1. Subsequently, by supplying the start pulses .phi..sub.s2 and .phi..sub.s3, the sensor signals of the line sensors 2 and 3 are similarly output through amplifiers A.sub.2 and A.sub.3, respectively.
However, in the conventional drive apparatus, a scanning circuit for each line is needed, so that there are problems such that the circuit scale enlarges, the bus line capacitances of the scanning circuits increase, and it is difficult to drive at a high speed.
On the other hand, there is also a problem such that the pitch among the line sensors is decided by the size of the scanning circuit and can be hardly set to a small pitch. Since the pitch cannot be reduced, for instance, in the case of constructing a 3-line color sensor of RGB, the optical characteristics deteriorate and the scale of the signal processing system increases.